I can't think of a product better suited to on-the-go music-lovers than headphones with Bluetooth connectivity and active noise cancellation (ANC). This is a relatively new category, offered by a handful of brands, including B&O, Definitive Technology, Parrot and Sennheiser.
Bluetooth gives you freedom of movement, because you're not tethered to your phone by an audio cable. Not only does Bluetooth carry music and voice wirelessly, it lets you control playback and phone calls right from the headphone.
ANC lets you enjoy your music in noisy environments like airline cabins and trains, without turning up the volume to ear-damaging levels. The technology works by sampling exterior sounds with tiny microphones around the earcups, then generating an out-of-phase signal that cancels out ambient sounds.
Because Bluetooth noise-cancelling headphones have their own built-in DACs and amplifiers, they have the potential to sound better than headphones that rely on the DAC and amplifier built into a smartphone or tablet. Of course, "potential" is the operative word here. Hence my eagerness to taking these four brand-new models for an extended test drive. Or should I say, "flight?"
How we tested: The review headphones arrived just as I was planning two short trips from my home in Toronto: one to Montreal and another to Boston. Given the general chaos characteristic of air travel, it was hard to do any rigorous testing on these jaunts, but they were a great opportunity to get the experience of using these 'phones. On the plane, in the airport and at the hotel, I just listened casually, playing whatever music struck my fancy at the time and noting my impressions. Airport and hotel listening was via Bluetooth. Up in the air, I switched my iPhone to Airplane mode, and used a wired connection, but with active noise cancellation engaged.
Back home, I replicated the flying experience in my third-floor music room by streaming airline cabin noise from the Internet through my sound system at 80dB. This had the advantage of better legroom and no security lines! And it gave me an opportunity to compare the phones' noise cancellation and sound quality in a much more controlled fashion than up in the air.
For the comparisons I performed at home, I chose five different tracks. To assess the headphones' noise cancelling, particularly their ability to produce quiet details in noisy environments, I played "Prelude à la Nuit," the atmospheric first movement of Maurice Ravel's Rhapsodie Espagnole for two pianos, played by Katia and Marielle Labèque (KML Recordings). To assess the ability to create a sense of pace and rhythm, and to accurately reproduce acoustic instruments, I played "Poinciana," an infectiously upbeat track from Whisper Not, a 1999 live concert recording by the Keith Jarrett Trio (ECM). To assess their ability to resolve complex, detailed music, and to deal with very wide dynamics, I played the dramatic opening of Carl Nielsen's Symphony No. 4 ("Inextinguishable"), played by the San Francisco Symphony under Herbert Blomstedt (London). I also wanted some well-recorded male and female vocals, so chose "Different Sides" from Leonard Cohen's Old Ideas (Sony Music), and "Maggie Said" from Natalie Merchant's 2014 self-titled album (Nonesuch). All of the files were CD rips in Apple Lossless format, played from my iPhone 6 Plus.
A few general remarks. All these 'phones have batteries that are charged via a micro USB jack on one of the earcups. They can all be used in passive mode with a direct connection when your battery runs low. But except for the Sennheiser Momentum Wireless, the sound in passive mode is more closed and muffled than it is in active mode. That's not surprising, because in active mode, the headphone is powered by a built-in amplifier, rather than the smaller amp inside your smartphone. In active mode, the sound is generally a little bit smoother with a direct connection than it is with Bluetooth.